Towards low-power electronics: self-recovering and flexible gas sensors

A new paradigm in recovery strategies for gas sensors is presented in this work. Resistive gas sensors based on carbon nanotubes (CNT) are well-known and show high sensitivity to different gas species but they require external recovery (i.e. heating) to offer a fast and stable response. In order to avoid this external element and reduce power demand, we demonstrate the possibility of recovering this kind of sensor by only applying a DC voltage. In particular, three different metals have been tested (Au, Ag and Al) to define interdigitated electrodes on a polyimide substrate. On top of them, CNT layers have been sprayed as a sensitive layer. The performance of these devices in terms of gas sensitivity, power consumption and stability is described and compared with external heating recovery. In particular, Au electrodes show a response to 2500 ppm CO2 of 2.6% with a recovery voltage of 5 V, presenting almost the same sensitivity as in the case of the external recovery at 80 degrees C but decreasing the power demand by more than 35 times.